1. Field of the Invention
The present invention relates to a method and apparatus for removing a film from a display panel. In particular, the present invention relates to a method and apparatus for removing successively and automatically the film that is stuck on the surface of a CRT (cathode ray tube) panel or thin display panel, typified by a PD (plasma display) panel. Moreover, the present invention relates to a method for manufacturing a new display panel by using a material obtained from a display panel after removal of the film.
2. Description of the Related Art
To recycle the cathode ray tubes (CRTs) of televisions or monitors that have been disposed of as glass, first, the CRTs should be divided generally into two portions: panels and funnels. Then, each of the portions is pulverized into small glass pieces (hereinafter, referred to as xe2x80x9cpelletsxe2x80x9d), and the pellets are used again as part of a CRT material.
In recent years, various resin films have been attached to a CRT surface to improve the function. However, the resin films mixed in pellets degrade the quality of CRT glass. Therefore, those resin films should be removed from the CRT surface beforehand. FIG. 5 shows a conventional process of removing a resin film.
As shown in FIG. 5, the resin film is peeled off manually by a worker in a conventional removal operation. This operation requires many man-hours, which in turn increases the cost. In general, the adhesive strength of the film becomes larger with time. Accordingly, a very large force is needed to remove the film, so that a heavy workload is imposed on the worker. Moreover, the above problem affects the recycling cost of CRTs and hampers the promotion of recycling CRTs.
In particular, when the adhesive strength between the CRT surface and an adhesive of the resin film is larger than that between a base film of the resin film and the adhesive, the adhesive is left on the CRT surface, while the base film is removed. This is so-called adhesive residue. The adhesive residue causes a defect when the remaining adhesive is mixed in the pellets because the adhesive also is made of a resin material. In this case, a worker again has to remove the adhesive that adheres to the CRT surface, e.g., with a metallic spatula, which becomes a heavy burden for the worker.
When the adhesive strength of an adhesive is more than 2000 g/inch (787 g/cm), it exceeds the breaking strength of a resin film. Therefore, the film may be ruptured during the removal operation. In this case, a portion of the resin film is not removed but is left on the CRT surface, so that a considerable amount of time and man-hours is necessary to remove the entire film.
When a resin film is not removed sufficiently from the CRT surface, the CRT with the resin film cannot be recycled and has to be disposed of as industrial wastes. However, such disposal is not preferable in view of environmental protection.
JP 7(1995)-31940 A discloses a method for removing a resin film with a water jet. According to this method, an injection nozzle having a plurality of injection holes that are arranged in line is rotated to inject water onto a resin film in the direction perpendicular to the film surface, and thus the resin film is removed and scattered by the jets of water.
However, the above method can remove only a resin film with relatively low strength that has a thickness of about 50 xcexcm because water is injected in the direction perpendicular to the film surface. Moreover, the amount and pressure of water required to remove the film becomes excessive for the same reason, which leads to an increase in size and operating cost of the apparatus.
JP 7(1995)-31940 A also discloses an apparatus for implementing the water-jet removal method. This apparatus includes a table for carrying an object on which a resin film is stuck and an injection nozzle that can move in both X and Y directions on the table.
However, the above apparatus has the disadvantage of increasing the cost of equipment because it is necessary to scan the injection nozzle in accordance with the shape of the object to remove the resin film. Moreover, the apparatus performs a batch-type removal operation, thus reducing efficiency.
Other removal methods, e.g., sandblasting, are known as well. The sandblasting uses an abrasive material to remove a resin film. Therefore, the abrasive material should be retrieved after removing the resin film. Moreover, a washer is needed to wash the abrasive material off the object from which the resin film has been removed.
Therefore, with the foregoing in mind, it is an object of the present invention to provide a method and apparatus for removing a film that can remove even a film with relatively high strength that is stuck on a display panel without relying on manual work and also can reduce the operating cost. It is another object of the present invention to provide a method for manufacturing a display panel that employs the film removal method and apparatus.
A method for removing a film from a display panel of the present invention includes subjecting a film stuck on a display panel to an injected liquid. The liquid is injected in the direction that tilts with respect to a normal to the surface of the display panel on which the film is stuck.
In the above method, it is preferable that the injection of the liquid is started at the boundary between one end of the film and the display panel so as to remove the film successively from said one end to the opposite end.
In this example, it is particularly preferable that the liquid is injected while transporting the display panel so that the film is removed successively from said one end to the opposite end. Moreover, it is preferable that the liquid is injected in the form of a fan.
The above method is effective when the display panel is one selected from a CRT panel and a PD panel. In this case, it is preferable that a height of the display panel is detected, and a position at which the liquid is injected is moved up or down in accordance with the height of the display panel.
In the above method, it is preferable that the removed film should be carried away by an air flow. Moreover, it is preferable that the angle between the direction of injection and the normal is in the range of 40 degrees to 50 degrees. It is preferable that the liquid is injected so that the injection pressure is in the range of 300 kg/cm2 to 1300 kg/cm2 and the flow rate is in the range of 10 l/min. to 50 l/min.
An apparatus for removing a film of the present invention is intended to remove a film stuck on a display panel by injecting a liquid. The apparatus includes a liquid injector. The liquid injector injects the liquid in a direction that tilts with respect to a normal to the surface of the display panel on which the film is stuck.
In the above apparatus, it is preferable that the liquid injector starts the injection of the liquid at the boundary between one end of the film and the display panel so as to remove the film successively from said one end to the opposite end.
The above apparatus further includes a carrier for transporting the display panel. It is preferable that the liquid is injected while transporting the display panel so that the film is removed successively from said one end to the opposite end.
A method for manufacturing a display panel of the present invention includes the following steps: removing a film from a display panel to be used as a material by injecting a liquid in the direction that tilts with respect to a normal to the surface of the display panel to be used as a material on which the film is struck; pulverizing the display panel to be used as a material after removal of the film; and melting a material including the pulverized display panel to be formed into a panel.
The film removal method and apparatus of the present invention easily can remove even a film that adheres firmly to the surface of a display panel in a short time without relying on manual work. Since chemical agents and abrasive materials are not used, the subsequent processes can be eliminated, thus minimizing a load on the environment.
The film removal apparatus of the present invention has a simple configuration that includes no large mechanical driving means other than a carrier, e.g., a conveyor, and thus it is easy to manufacture the apparatus. Therefore, the apparatus can be provided inexpensively, which leads to a reduction in initial cost.
The method for manufacturing a display panel of the present invention easily can remove a film that is stuck on a display panel to be used as a material in a short time, so that the manufacturing cost can be reduced.